I'm not a noob but my issue probably seems like one...I recently sent 5 beers to a competition and 2 of the beers had comments about oxidation. I have been brewing for 3 years and have continued to improve much of my process during brew day but have neglected bottling. I was bottling a beer a few days ago and noticed a small layer of very small bubbles on the top of every beer I bottled. I thought this was occuring because I had the flow rate very fast and as the beer entered the bottle, it was getting agitated. To counteract this I closed the spigot some. When I did this I noticed that just under the spigot looked to be a tornado in the tubing, and very small bubbles farther down the tubing just before the bottle filler. I thought air might be coming in from the small hole on the front of the spigot so I covered that but it didn't help. I put a hose clamp on the spigot, but that didn't help either.

First of all, why did there appear to be a tornado in my tubing when I started to close the spigot?

Is there another way to slow the flow rate down rather than closing the spigot?

Any other tips on preventing oxidation during bottling would be greatly appreciated.

Your oxidation is not coming from this little tiny bit of air in the beer, I can assure you of that. How old were the two bottles you sent in? My guess is that you had a few bottles with a bad seal on them. If you're seriously worried about oxidation at bottling time, try using oxygen barrier caps.

As for tornados...fluid dynamics, my friend. The liquid is always flowing through your tubing like this, you probably just didn't notice it until you slowed it down and allowed a little air pocket to form.

__________________He who drinks beer sleeps well. He who sleeps well cannot sin. He who does not sin goes to heaven.

The two bottles were probably 6-8 months old. These bottles as well as all my other beers have the oxygen barrier caps on them. Maybe I need a new bottle capper.
Can you elaborate a little on why you seem adamant the oxidation isn't coming from the tiny air bubbles?

Can you elaborate a little on why you seem adamant the oxidation isn't coming from the tiny air bubbles?

Because, if it were coming from air bubbles at bottling time, every one of us would experience the same thing. We all use the same equipment, and the same techniques. The little bit of oxygen that makes it in through those bubbles isn't near enough for someone to notice. I have yet to experience an oxidized beer, and I've got beers that are 2+ years old sitting in my pantry.

__________________He who drinks beer sleeps well. He who sleeps well cannot sin. He who does not sin goes to heaven.